Cutting fluid composition of chlorofluoro- and nitroalkanes

ABSTRACT

CUTTING FLUID COMPOSITIONS COMPRISING TRICHLOROFLUOROMETHANE OR 1,1,2-TRICHLORO-1,2,2-TRIFLUOROETHANE AND FROM ABOUT 6 PERCENT TO 15 PERCENT BY WEIGHT OF A NITROALKANE HAVING 1 OR 2 CARBON ATOMS.

M. B. PARKER 3,634,247

CUTTING FLUID COMPOSITION OF CHLOROFLUORO- AND NITROALKANES Jan. 11,1972 'Filed Jan. 9, 1970 NITROHETHANE BY WT. IN CCL F) INVENTOR MURRAYBORTON PARKER United States Patent O T 3,634,247 CUTTING FLUIDCOMPOSITION OF CHLORO- FLUORO- AND NITROALKANES Murray Borton Parker,Hockessin, Del., assignor to E. I. du Pont de Nemours and Company,Wilmington, Del. Filed Jan. 9, 1970, Ser. No. 1,813 Int. Cl. Cm 1/30,1/32 U.S. Cl. 252-515 R 4 Claims ABSTRACT OF THE DISCLOSURE Cuttingfluid compositions comprising trichlorofluoromethane or1,1,Z-trichloro-1,2,2-trifluoroethane and from about 6 percent topercent by weight of a nitroalkane having 1 or 2 carbon atoms.

BACKGROUND OF THE INVENTION (1) Field of the invention This inventionrelates to a cutting fluid composition comprising a chlorofluoroalkaneselected from trichlorofluoromethane or1,l,2-trichloro-l,2,2-trifluoroethane and nitromethane or nitroethane.

(2) Description of the prior art SUMMARY OF THE INVENTION The presentinvention is directed to a cutting fluid composition comprising achlorofluoroalkane and a nitroalkane. The chlorofluoroalkane is either1,1,2-trichloro- 1,2,2-trifluoroethane or trichlorofluoromethane and thenitroalkane which is present in an amount of from about 6 percent to 15percent by weight of the cutting fluid, has either 1 or 2 carbon atoms.

DESCRIPTION OF THE DRAWING The figure is a plot of nitrolkaneconcentration in a cutting fluid composition of the invention versustool life in drilling aluminum alloy. The curve represents theperformance when the fluid feed rate was 2 lbs. (0.9 kg.)/hr. and theair flow rate was 2.03 standard cu. ft. (57.5 1iters)/min.

DESCRIPTION OF THE INVENTION The present invention comprises anevaporative cutting fluid composition which may be used in machining ametal, e.g., in drilling, routing, lathe turning, etc., said cuttingfluid composition comprising a chlorofluoroalkane and from about 6% to15% by weight of a nitroalkane having 1 or 2 carbon atoms. Whenmachining a metal the manner of application of the cutting fluid, whilenot critical, is normally selected from two primary methods. The firstmethod is the application of the cutting fluid as a solid stream and thesecond method is the application of the cutting fluid in droplet form,said droplets being dispersed and evaporated in a stream of compressedair by means of a misting nozzle. It has been found that the latterprocess prolongs tool life substantially more than does the solid streammethod.

Patented Jan. 11, 1972 The chlorofluoroalkanes which may be used in thecutting fluids of the present invention are 1,1,2-trichloro-1,2,2-trifluoroethane and trichlorofluoromethane. The nitroalkanes arenitromethane and nitroethane. As will be seen in Examples 1 and 2, anincrease in the amount of the nitroalkane in the cutting fluidcomposition from about 6% to 15 by weight, results in a correspondentincrease in tool life. Tool life may also be increased by increasing therate of application of the cutting fluid in both solid stream andmisting nozzles.

All variables in the manner of application of the cutting fluid are notentirely independent. For example, the employment of large volumes ofair permits the use of lesser amounts of cutting fluid of constantnitromethane content to obtain the same tool life.

Practical limits exist as well, for example, with misting nozzles,application of more than about eight pounds (3.6 kg.) per hour willcause fluid to accumulate on the 'work. Similarly, concentrations ofmore than about 15% nitromethane will cause nitromethane residues toaccumulate on the work. The efliciency of the misting nozzle in terms ofdispersion of the cutting fluid droplets in the air and the amount ofco-dispensed air will naturally affect the accumulation of liquid on thework. Nitroalkanes of higher molecular weight than nitromethane althoughoperable are more likely to accumulate on the work because of lesservolatility.

In utilizing the cutting fluids of the invention, the preferred cuttingfluid composition is an approximately 8% by weight solution ofnitromethane in trichlorofluoromethane. It is preferred to apply thissolution at the rate of about 2 to about 6 lbs. (0.9 to 2.7 kg.) perhour through a misting-type nozzle with about 1 to about 2 standard cu.ft./ min. (23 to 57 liters/min.) co-dispensed air. It is also preferableto adjust the rates of these two components within these limitsaccording to the quality of the cutting machine and the particularoperation.

Precautions should be taken in confined areas to protect personnel fromthe accumulation of excessively high concentrations of cutting fluidvapors. Standards set by the American Conference of GovernmentalIndustrial Hygienists allow a Threshold Limit Value (TLV) of 1,000p.p.m. for the fluorocarbon portion of the cutting fluid and p.p.m. fornitroethane or nitromethane. The vapors of compositions within the rangeof this invention are of a lower order of toxicity and nonflammable. Ifgross evaporation occurs (more than 50% by volume), the compositionbecomes richer in nitroalkane until it eventually becomes flammable.

The following examples are intended to be merely illustrative of theinvention and not in limitation thereof. Unless otherwise indicated, allparts are by weight.

EXAMPLES The utility and effectiveness of the cutting fluid compositionsof this invention were evidenced by a determination of the relative toollife in machining metal in contact with these cutting fluids.

Relative tool life was estimated in drilling by counting the number ofholes drilled in aluminum alloy and in 316 stainless steel specimensunder standard conditions before the cutting edge of the drill, asmeasured across the flutes at the circumference, had worn away 0.015inch (0.038 mm.). This was measured by means of a scaled occular 40power microscope.

The aluminum alloy test specimens consisted of two 4 x 6 inch (10.2 x15.2 cm.), 4 inch (6.35 mm.) thick plates of 7075-T6 aluminum alloybolted together. The alloy is described in Chemical Engineers Handbook,Mc- Graw-Hill Book Co., New York, N.Y., Fourth edition, pp. 23-40 and iscommonly used in the aircraft industry. The drill passed through bothpieces, i.e., through 0.5 inch (12.7 mm.) of metal.

The 316 stainless steel test pieces consisted of four 4 x 6 inch (10.2 x15.2 cm.), /8 inch (3.2 mm.) thick plates bolted together.

The test drills used in drilling the aluminum alloy were A inch (6.35mm.) No. 957 high helix twist drills manufactured by the Cleveland TwistDrill Co. of Cleveland, Ohio. Drills from a single lot were used in eachtest. The drills turning at 3640 revolutions per minute were advancedinto the work at the steady rates shown in examples.

The drills used in drilling the stainless steel were A inch (6.35 mm.)N0. 817 Cobalt 135 split point drills also manufactured by the ClevelandTwist Drill Co.

Cutting fluid was delivered to the work by nozzles placed at an angle ofabout to the work and directed to the drill hole. The nozzles useddelivered mists consisting of droplets of a cutting fluid composition ofthis invention dispersed in a stream of compressed air.

The nozzle utilized in Example 1, hereinafter called the venturi nozzle,is manufactured by the Mamco Mfg. Co. of Seattle, Wash. The nozzle ischaracterized in that the cutting fluid is aspirated from the peripheryof a central air channel. Cutting fluid is supplied to the peripheryslightly upstream from the venturi inner nozzle through a sinteredstainless steel ring, the inner portion of which was open to the airchannel. Fluid was supplied to the outer periphery of the sintered ring.Air, mixed with aspirated cutting fluid droplets, is carried thereafterthr-ough an approximately A1 inch (6.4 mm.) diameter tube about 1 inch(2.5 cm.) long where the mixture leaves the nozzle. Hereinafter thenozzle is referred to as the venturi nozzle.

A second misting nozzle which was used in Example 2 was the so-calledSpraymist nozzle manufactured by the Bijur Lubricating Corp. of RochellePark, NJ. That companys flexible extension jet which they designateB-101 and their jet tip designated B-136 were used. The nozzle ischaracterized in that compressed air and cutting fluid are supplied tothe nozzle head by means of two concentric tubes, the cutting fluidbeing in an inner tube and the compressed air in an annular space. Theconcentric tubes enter a spray head of relatively large volume fromwhich the mixture exits at the opposite end through a 0.050 inch (1.27mm.) diameter hole. There is considerable turbulence therein thusassuring good mixing. This nozzle is hereinafter referred to as the pressure-drop nozzle.

In these experiments with misting nozzles, compressed air was suppliedto the nozzles at the pressures stated in examples. In the exampleswhere air flow is stated, the flow was measured by a calibrated floatingbob device. Fluid flows were measured by following the loss in weight ofthe supply tank and additionally by a calibrated floating bob device.

In the examples wherein standard deviation is stated, the averageperformance of three drills and the standard deviation in three paralleltests is reported.

EXAMPLE 1 This example demonstrates the utility of the compositions ofthe present invention as cutting fluids in drilling 316 stainless steel.

The conditions of the experiment were the following:

Application by: Venturi nozzle Fluid flow rate: 4 lbs. (1.8 kg.)/hr.

Air flow: 2.4 s.c.f. (68.0 liters) /m Fluid pressure: p.s.i.g. (281 kg/C1112) Air pressure: '80 p.s.i.g. (5.62 kg/cm?) Drill speed: r.p.m.-Drill advance rate: 003 in. (0.076 mm.)/sec.

The results are shown in the table below.

EXAMPLE 2 Effect of nitromethane concentration in trichlorofluoromethaneand other variables in high quality drill press drilling of aluminumThis example demonstrates the utility of compositions of this inventionas cutting fluids in a high quality drill press and also the fact thatperformance, as reflected in extended tool life, depends on nitromethaneconcentration.

The conditions of the examples were:

Application by: Pressure drop nozzle Drill advance rate: 0.006 in. (0.15mm.)/revolution In this experiment whose results are shown by the curveof the figure, fluid was applied at the rate of 2 lbs. (0.9 kg.)/hr.;air was co-dispensed in the experiment at the rate of 2.03 standard cu.ft. (57.5 liters)/min. It may be readily seen from this curve that anincrease in nitroalkane concentration, between 6 and 15% 'by weight,results in a corresponding increase or extension of tool life.

The foregoing detailed description has been given for clearness ofunderstanding only and no unncessary limitations are to be understoodtherefrom. The invention is not limited to the exact details shown anddescribed for obvious modifications will occur to those skilled in theart.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A cutting fluid composition comprising a chlorofluoroalkane selectedfrom the group consisting of trichlorofluoromethane and 1,1,2 trichloro1,2,2-trifluoroethane, and from about 6 percent to 15 percent by weightof a nitroalkane having 1 or '2 carbon atoms.

2. A cutting fluid composition according to claim 1 wherein thechlorofluoroalkane is 1,l,2-trichloro-1,2,2- trifluoroethane and thenitroalkane is nitromethane.

3. A cutting fluid composition according to claim 1 wherein thechlorofluoroalkane is trichlorofluoromethane and the nitroalkane isnitromethane.

4. A cutting fluid composition according to claim 3 comprisingtrichlorofiuoromethane and about 8 percent by weight of nitromethane.

References Cited UNITED STATES PATENTS 3,085,116 4/1963 Kvalnes 260-65253,129,182 4/1964 McLean 252-54 DANIEL E. WYMAN, Primary Examiner W. J.SHINE, Assistant Examiner U.S. Cl. X.R. 252-58

